The Commonwealth Jack was the flag of the Commonwealth of England which replaced the Kingdom of England in 1649. In contrast to the Union Jack which it replaced, it consisted of just two symbols. The left two quadrants contained an elogated version of St George's Cross, representing England, while the right two quadrants contained an Irish harp symbolising Ireland. The Commonwealth Jack contained no representation for Scotland or Wales.

The flag was replaced by the Protectorate Jack in 1658. It in turn was replaced by the returned Union Jack in 1660, following the restoration of the monarchy and of the Kingdoms of England, Scotland and Ireland.